JP2006196304A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device reduced in size and restrained in cost by simplifying a multiplied voltage rectification circuit without providing a discharge lamp starting winding in a transformer installed in a D.C./D.C. converter. <P>SOLUTION: This discharge lamp lighting device is provided with: a control part 4 for controlling output voltages by connecting a D.C./D.C. converter having a transformer T1 and a D.C./D.C. converter having a transformer T2 in parallel with each other and varying the respective duties thereof while shifting operation phases of the transformers T1 and T2 of the respective D.C./D.C. converters; and the multiplied voltage rectification circuit adapted to generating a high voltage used for starting of the discharge lamp 22 by using a potential difference between the output voltages of the transformers T1 and T2 and comprising diodes 7-9 and capacitors 10-12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a discharge lamp lighting device that includes a DC / DC converter and lights a discharge lamp.

When lighting a discharge lamp, it is first necessary to apply a high voltage between the electrodes of the discharge lamp to cause dielectric breakdown (breakdown) between the electrodes. For dielectric breakdown between the electrodes, the charge accumulated in the capacitor is suddenly discharged to the primary winding of the ignition (hereinafter referred to as IGN) transformer, and at this time, an impulse is generated in the secondary winding of the IGN transformer. High voltage is used.
If the voltage discharged from the capacitor to the primary winding of the IGN transformer is set high, the primary / secondary winding ratio of the IGN transformer can be reduced. In other words, if the voltage applied to the primary winding of the IGN transformer is increased, the number of turns of the secondary winding can be reduced, so the resistance is reduced by using a thick wire, and the IGN transformer is downsized. It becomes possible to do. Therefore, the discharge lamp lighting device is provided with a circuit for applying a high voltage to the IGN transformer.

A conventional discharge lamp lighting device includes a step-up transformer that boosts the voltage of an AC power source, and a DC high voltage is generated by a voltage doubler rectifier circuit including a plurality of diodes and the like configured on the secondary side of the step-up transformer. The capacitor is charged with the DC high voltage, and the discharge lamp is started using the electric charge stored in the capacitor (see, for example, Patent Document 1).
Further, the DC voltage output from the lighting circuit is intermittently applied by a switching element such as Sidac and applied to the primary winding of the transformer, and the boosted AC voltage is output from the secondary winding, and this AC voltage is output. Is supplied to a voltage doubler rectifier circuit, a high voltage is generated, the capacitor is charged using this high voltage, and the electric charge discharged from the capacitor is supplied to the IGN transformer in the same manner as described above, and the discharge lamp is turned on. (For example, refer to Patent Document 2).

  In addition, a DC booster circuit having a transformer, a DC-AC conversion circuit, and a start pulse generation circuit are provided, and a high voltage pulse is generated from a capacitor included in the start pulse generation circuit in synchronization with the operation of the DC-AC conversion circuit. Some output voltage to start a discharge lamp. The secondary side of the transformer of the DC booster circuit is provided with a winding used to generate a high voltage for starting the discharge lamp, and the starting pulse circuit accumulates electric power supplied from this winding in a capacitor. When the terminal voltage of the capacitor reaches a predetermined value, the self-breakdown switch element provided in the starting pulse circuit breaks down. The pulse voltage generated at this time is superimposed on the pulse voltage output from the bridge circuit forming the DC-AC conversion circuit, and this voltage is applied to the discharge lamp to start lighting (see, for example, Patent Document 3). ).

  The self-breakdown switching element provided in the above-described starting pulse generation circuit has, for example, an air gap that breaks down and becomes conductive when a voltage of about 1000 V is applied. That is, this starting pulse generation circuit charges the capacitor using a voltage of 1000 V or more. When trying to generate a high voltage of about 1000V by a voltage doubler rectifier circuit, it is generated by inputting a high voltage of 500V or higher, or if the input is about 300V, the voltage doubler rectifier circuit is configured as a frequency multiplier of 3x or higher. I will let you. When a high voltage of about 1000 V is generated, the circuit is configured with a high breakdown voltage, or the circuit that generates the multiplied voltage is configured with a large number of components. A high voltage is obtained by using an AC conversion circuit and a starting pulse generation circuit. Actually, it is desirable to generate a triple voltage and obtain a high voltage.

JP 59-196594 (pages 2, 3 and 2) JP-A-9-69393 (pages 4, 5 and 1) Japanese Patent Laid-Open No. 7-142182 (pages 3, 4 and 1)

  Since the conventional discharge lamp lighting device is configured as described above, a multiplied voltage rectifier circuit is arranged on the output side of a DC-AC converter circuit (DC / AC inverter) that outputs an AC voltage having a relatively low frequency. Therefore, the charging time of the capacitor of the IGN circuit for starting the discharge lamp becomes longer, and a capacitor having a large capacity is required for the multiplied voltage rectifier circuit. In addition, there is a problem that the number of parts constituting the circuit increases and it is difficult to reduce the size.

  The present invention has been made to solve the above-described problems, and does not provide a winding for starting a discharge lamp in a transformer provided in a DC / DC converter, and simplifies a multiplied voltage rectifier circuit. An object of the present invention is to obtain a discharge lamp lighting device capable of reducing the size and cost.

  A discharge lamp lighting device according to the present invention includes a plurality of DC / DC converters having a transformer for boosting a power supply voltage and connected in parallel, and control means for controlling the operation phases of the transformers of each DC / DC converter to shift, And a multiplying voltage rectifier circuit that generates a high voltage used for starting a discharge lamp using a potential difference between output voltages of the transformers.

  According to the present invention, the control means for controlling the operation of each transformer of the plurality of DC / DC converters to shift the phase of the output voltage, and the high voltage used for starting the discharge lamp using the potential difference between the output voltages of each transformer. Therefore, it is possible to reduce the size and reduce the cost.

An embodiment of the present invention will be described below.
Embodiment 1 FIG.
1 is a circuit diagram showing a discharge lamp lighting device according to Embodiment 1 of the present invention. One end of the primary winding of the transformer T1 and one end of the primary winding of the transformer T2 are connected to the positive electrode of the power source 1 that supplies DC power. A switching element 2 for turning on / off the connection with the negative electrode of the power source 1 is connected to the other end of the primary winding of the transformer T1. A switching element 3 for turning on / off the connection with the negative electrode of the power source 1 is connected to the other end of the primary winding of the transformer T2. The control unit (control means) 4 is connected to the control signal input terminals and the like of the switching elements 2 and 3.

One end of the secondary winding of the transformer T1 is connected to the anode of the diode 5, the anode of the diode 7, and one end of the capacitor 10. One end of the secondary winding of the transformer T2 is connected to the anode of the diode 6 and one end of the capacitor 11. The other end of the capacitor 11 is connected to the cathode of the diode 7. The anode of the diode 8 is connected to the cathode of the diode 7, and the anode of the diode 9 is connected to the cathode of the diode 8. That is, the diodes 7 to 9 are connected in series. The other end of the capacitor 10 is connected to a connection point between the diode 8 and the diode 9.
The cathode of the diode 5 is connected to the cathode of the diode 6, and further connected to one end of the capacitor 12, one end of the capacitor 13, and the transistors 14 and 16. This connection point is grounded. The other end of the secondary winding of the transformer T2 is connected to the other end of the secondary winding of the transformer T1, and the other end of the capacitor 13 and transistors 15 and 17 are connected.

The switching element 2, the control unit 4, the transformer T1, the diode 5, and the capacitor 13 connected as described above constitute a DC / DC converter that boosts the DC voltage of the power supply 1. Further, the switching element 3, the control unit 4, the transformer T2, the diode 6 and the capacitor 13 constitute a DC / DC converter similar to the above, and the discharge lamp lighting device shown in FIG. Two DC / DC converters are provided. The outputs of these two DC / DC converters are combined as a voltage across the capacitor 13 and supplied to a DC / AC inverter described later.
The diodes 7 to 9 and the capacitors 10 to 12 constitute a multiplied voltage rectifier circuit. This multiplied voltage rectifier circuit generates a voltage twice the DC / DC converter output voltage by combining with two DC / DC converters, and supplies it to an IGN circuit to be described later.

  Transistor 14 and transistor 15 are connected in series, and transistor 16 and transistor 17 are connected in series. When an H-type bridge circuit is configured by the transistors 14 to 17 and, for example, an n-channel FET is used as the transistors 14 to 17, the source of the transistor 14 and the drain of the transistor 15 are connected, and the source of the transistor 16 and the drain of the transistor 17 are connected. Is connected. The drain of the transistor 14 and the drain of the transistor 16 are connected, and the source of the transistor 15 and the source of the transistor 17 are connected. In this configuration, the drains of the transistors 14 and 16 are connected to the cathodes of the diodes 5 and 6 and one ends of the capacitors 12 and 13 as described above, and the sources of the transistors 15 and 17 are the transformers T1 and T2. Are connected to the other end of the secondary winding and the other end of the capacitor 13.

  One electrode of the discharge lamp 22 is connected to a connection point between the transistor 14 and the transistor 15. One end of the capacitor 20 and the primary winding terminal of the IGN transformer T3 are connected to a connection point between the transistor 16 and the transistor 17. The ON / OFF operation of the transistors 14 to 17 is controlled by the control unit 18. When the n-channel FET is used as the transistors 14 to 17 as described above, the control unit 18 is connected to the gates of the transistors 14 to 17. Each gate voltage is controlled. The transistors 14 to 17 and the control unit 18 connected as an H-type bridge circuit constitute a DC / AC inverter that supplies an AC voltage to the discharge lamp 22.

The other electrode of the discharge lamp 22 is connected to the secondary winding terminal of the IGN transformer T3. One end of a resistor 19 is connected to the cathode of the diode 9, and the other end of the resistor 19 is connected to the other end of the capacitor 20 and one terminal of the GAP switch 21. The GAP switch 21 is an open / close switch that becomes conductive when a high voltage is applied to both terminals, and has a discharge gap that causes breakdown and becomes conductive when a high voltage of, for example, about 800 V is applied. The IGN transformer T3 is an autotransformer in which a part of the primary winding and the secondary winding are shared, and the other terminal of the GAP switch 21 is connected to the common terminal of the primary winding and the secondary winding. ing. The IGN circuit that activates the discharge lamp 22 is configured by the IGN transformer T3, the resistor 19, the capacitor 20, and the GAP switch 21 connected in this manner.
Further, the control unit 4 is connected so as to detect, for example, the voltage across the capacitor 13 so as to detect the output voltage of the DC / DC converter used for lighting the discharge lamp 22, and for example, between the capacitor 13 and the transistors 15 and 17. Connected to the connection point.

Next, the operation will be described.
When starting the discharge lamp 22, the control unit 18 controls the transistors 14 and 17 to be in an ON state and the transistors 15 and 16 to be in an OFF state. In this state, the control unit 4 controls the operation of the switching elements 2 and 3 to generate a high voltage in the secondary windings of the transformers T1 and T2. A voltage of 400 V is applied to the discharge lamp 22 through the transistors 14 and 17 in the ON state as described above. Note that the voltage across the capacitor 13 is the output voltage of the DC / DC converter. The output voltage of the DC / DC converter is a lighting voltage for lighting the discharge lamp 22 after startup.

  As described above, the pulse voltage generated in the secondary windings of the transformer T1 and the transformer T2 is boosted using the multiplied voltage rectifier circuit composed of the diodes 7 to 9 and the capacitors 10 to 12, thereby generating a high DC voltage. The voltage is applied to the capacitor 20 through the resistor 19. When the capacitor 20 is charged and the voltage across the capacitor 20 reaches a predetermined high voltage and the GAP switch 21 is closed, the power stored in the capacitor 20 is supplied to the primary coil of the IGN transformer T3. At this time, the pulse voltage generated in the secondary coil of the IGN transformer T3 is superimposed on the lighting voltage applied from the capacitor 13 to the discharge lamp 22, and discharge between the electrodes of the discharge lamp 22 is started. When the discharge lamp 22 is activated, the control unit 18 alternately turns on and off the transistors 14 and 17 and the transistors 15 and 16, switches the direction of the current flowing from the DC / DC converter to the discharge lamp 22, and supplies the AC to the discharge lamp 22. A voltage is supplied to stabilize discharge lighting and to perform steady lighting. The discharge lighting device according to the first embodiment operates generally in this way to light the discharge lamp 22.

The discharge lighting device according to Embodiment 1 of the present invention is characterized by the operation of starting the discharge lamp 22 in the above operation. Here, the description of the operation when steady lighting is performed under the control of the control unit 18 is omitted.
The transformer T1 and the transformer T2 perform flyback type operation. For example, the transformer T1 stores power supplied from the power source 1 to the primary winding when the switching element 2 is in an ON state, and the switching element 2 is turned off. When the stored power is output from the secondary winding. The transformer T2 performs an output operation in the same manner when the switching element 3 is turned ON / OFF.
FIG. 2 is an explanatory diagram showing the operation of the discharge lamp lighting device according to the first embodiment. This figure is a timing chart showing voltage waveforms output from the secondary windings of the transformers T1 and T2. The waveform shown as “less than 50% duty” in the upper part of the figure shows that the ON / OFF duty ratio (hereinafter referred to as ON duty ratio) of the switching elements 2 and 3 is less than 50%, and the ON state is shorter than the OFF state. This is the output waveform. The waveform shown as “duty 50%” in the middle of the figure is a waveform when the ON duty ratio of the switching elements 2 and 3 is 50%, that is, the period of the ON state and the OFF state is equal. The waveform shown as “duty 50% or more” in the lower part of the figure is an output waveform when the ON duty ratio of the switching elements 2 and 3 is 50% or more and the ON state is longer than the OFF state.

The switching element 2 and the switching element 3 are controlled to be turned ON / OFF alternately by the control unit 4. The primary side windings of the transformer T1 and the transformer T2 are connected in parallel to the power source 1, and current flows alternately to the primary side windings by the switching elements 2 and 3 that are alternately turned on and off. .
Explaining the transformer T1 as an example, in the flyback operation, when the switching element 2 is OFF, for example, a voltage E boosted to a high voltage is output. When the switching element 2 is ON, the number of turns of the primary winding of the transformer T1 is N1, the number of turns of the secondary winding is N2, and the voltage input from the power source 1 is VIN. In this case, the voltage e obtained as e = VIN · N2 / N1 is output from the transformer T1. The transformer T1 and the transformer T2 alternately output asymmetric pulse voltages, for example, a positive voltage E and a negative voltage e as shown in FIG.

  When the GAP switch 20 is turned on, a high voltage power supply of 1000 V or more is required. Therefore, the multiplied voltage rectifier circuit including the diodes 7 to 9 and the capacitors 10 to 12 shown in FIG. 1 includes two transformers T1 and T2. A high voltage is generated by using the peak-to-peak voltage obtained by superposing the output voltage difference between the output voltages of the transformers T1 and T2. As will be described later, when the potential difference between the output voltages of the two transformers T1 and T2 is large, a high voltage can be easily generated, and the capacitor 20 constituting the IGN circuit can be quickly charged by this high voltage. It becomes possible. In addition, compared to the case where the output voltage of one transformer is used, the multiplied voltage rectifier circuit can be configured with a smaller number of diodes and capacitors.

  For example, when the output voltage of the transformer T1 and the output voltage of the transformer T2, which are out of phase by 180 ° as in the waveform shown as “duty 50%” in the middle stage of FIG. 2, are superimposed, the voltage value of Peak to Peak is E + e. It becomes. When two transformers are used in this way, for example, each ON state of the switching element 2 is shorter than the OFF state and accumulated in the transformer T1 as shown in the waveform shown as “less than 50% duty” in the upper part of FIG. When the power is not sufficient, the pulse voltage output from the transformer T1 while the switching element 2 is in the OFF state maintains the voltage E for a short period, and then drops to, for example, the GND level so that there is no voltage output. Arise. If the output voltage disappears after the transformers T1 and T2 output the voltage E for a short period in this way, for example, it becomes difficult to sufficiently store charges in the capacitor 11 constituting the multiplied voltage rectifier circuit. It will not be possible to operate normally.

  In order to operate the multiplied voltage rectifier circuit normally, as shown in the waveform of “duty 50%” shown in the middle stage of FIG. 2, a pulse voltage having the same ON state and OFF state period is output from the transformer T1 and the transformer T2, and always. It is preferable to control the operation of the switching elements 2 and 3 so that a voltage of E + e is obtained when these output voltages are superimposed, or like the waveform of “duty 50% or more” shown in the lower part of FIG. The transformers T1 and T2 are operated so as not to lose voltage output. That is, the transformers T1 and T2 are operated so that the high-side output voltage E and the low-side output voltage e output from the transformers T1 and T2 respectively overlap.

As described above, the control unit 4 operates so that the ON / OFF timing of the switching element 2 and the ON / OFF timing of the switching element 3 are shifted by 180 °, and the ON duty ratio becomes 50% or 50% or more. In this way, the switching element 2 and the switching element 3 are operated so that the potential difference between the output voltage of the transformer T1 and the output voltage of the transformer T2, that is, the voltage E + e, is input to the multiplied voltage rectifier circuit. Preferably, the ON duty ratio is set to 50% so that the voltage E + e is maintained for a long time.
In this way, the control unit 4 operates each of the DC / DC converters including the transformers T1 and T2 and further the transformer T1 or the transformer T2 so as to supply a large potential difference from the transformers T1 and T2 to the multiplied voltage rectifier circuit as long as possible. And supply as much power as possible to the multiplied voltage rectifier circuit.

  The voltage output from the transformer T1 is applied to one end of the capacitor 11 via the diode 7, the voltage output from the transformer T2 is applied to the other end of the capacitor 11, and the capacitor 11 is charged. Generate voltage. A voltage E + e is applied to the anode of the diode 8 by the capacitor 11, and a voltage 2E + 2e is generated across the capacitor 10 charged via the diode 8. One end of a capacitor 12 is connected to the cathode of the diode 9 to which this voltage 2E + 2e is input, and the voltage across the capacitor 12 is 2E + 2e. The capacitor 12 and the capacitor 13 are connected in series, and a potential difference of 3E + 2e is generated at both ends of the series capacitor of the capacitor 12 and the capacitor 13, for example, a high voltage of about 1200V is generated.

  A current is supplied to one end of the capacitor 20 from a connection point between the diode 9 and the capacitor 12. The capacitor 20 is charged by this current, and the voltage at both ends is increased to the voltage 3E + 2e when charging the maximum voltage. When the capacitor 20 is charged in this way and both ends thereof reach a predetermined high voltage of 800 V or more, the GAP switch 21 is closed, the discharge current of the capacitor 20 flows through the primary coil of the IGN transformer T3, and the secondary coil of the IGN transformer T3. A high voltage pulse voltage is generated. This pulse voltage is applied to the discharge lamp 22 to start lighting.

When starting the discharge lamp 22, it is necessary to charge both the capacitor 13 and the capacitor 20 so that both ends thereof have a predetermined high voltage. When the discharge lamp 22 is steadily lit, a voltage of about 400 V may be applied in advance to the discharge lamp 22 before breakdown, and the capacitor 13 maintains the voltage necessary for this steady lighting, that is, the lighting voltage as a voltage across the two ends. Thus, power is supplied from the transformers T1 and T2.
In general, when the voltage across the capacitor 13 reaches a predetermined value, the ON duty ratio of the transformers T1 and T2 is adjusted so as to keep this voltage constant. When the current is adjusted by changing the ON duty ratio as described above, the ON duty ratio described with reference to FIG. 2 becomes less than 50%, and the operation of the multiplied voltage rectifier circuit becomes defective.

  When charging the capacitor 13 and the capacitor 20 to start the discharge lamp 22, the voltage across the capacitor 13 first reaches a high voltage of, for example, about 400V. If control is performed to reduce the ON duty ratio of the transformers T1 and T2 in response to this, the capacitor 20 cannot be charged sufficiently, and the voltage across the capacitor 20 does not reach a high voltage of about 800V, for example. The GAP switch 21 cannot be closed.

  In the discharge lamp lighting device according to the first embodiment, the control unit 4 fixes the ON duty ratio of the transformers T1 and T2 to 50% or 50% or more, and performs an intermittent operation by providing a period for performing an output operation and a period for resting. ing. In this way, intermittent operation is performed by keeping the ON duty ratio of the transformers T1 and T2 constant, for example, 50%, so that the DC / DC converter and the multiplied voltage rectifier circuit are effectively operated and the voltage across the capacitor 13 is set to a predetermined value. And the capacitor 20 is charged. That is, by reducing the ON duty ratio, the charging current supplied to the capacitor 13 whose both-ends voltage has reached the lighting voltage is not suppressed, but a certain amount of charging current is supplied and the supply is stopped. By repeating the above, the voltage across the capacitor 13 is kept at the lighting voltage. In this operation, since the ON duty ratio is always constant, a predetermined voltage such as E + e is input to the multiplied voltage rectifier circuit, and the multiplied voltage rectifier circuit normally generates a high voltage to charge the capacitor 20. It can be done effectively.

FIG. 3 is an explanatory diagram showing the operation of the discharge lamp lighting device according to the first embodiment. This figure is a timing chart showing output voltages of the transformer T1 and the transformer T2. As shown in the figure, the control unit 4 operates the transformer T1 and the transformer T2 at the same time and pauses them. The controller 4 is connected so as to detect the voltage across the capacitor 13 as described above, and controls the switching elements 2 and 3 until the voltage across the capacitor 13 reaches, for example, 400 V, so that the transformers T1, T2 To output rectangular wave voltages whose phases are shifted from each other.
Since one end of the capacitor 13 serving as the high-side output point of the DC / DC converter is grounded, the voltage of the capacitor 13 detected by the control unit 4 is a negative value when viewed from the GND level. "400V" becomes -400V. In the following description, the voltage across the capacitor 13 will be described as a potential difference across the capacitor 13 rather than an absolute value viewed from the GND level.

  When the detected potential difference reaches 400 V, the control unit 4 stops the ON / OFF operation of the switching elements 2 and 3 and stops the output operation of the transformers T1 and T2. When the detected potential difference becomes smaller than a predetermined value, that is, when it becomes less than 400 V, the switching elements 2 and 3 are operated, and a voltage is output from the transformers T1 and T2. Thus, the control unit 4 causes the DC / DC converter including the transformer T1 and the DC / DC converter including the transformer T2 to intermittently operate. Further, since these DC / DC converters are both configured to hold the output voltage by the capacitor 13, the control unit 4 controls so that the intermittent operations of the two DC / DC converters are synchronized. In this operation, since the ON duty ratio of the transformers T1 and T2 is always constant, for example, 50%, a constant high voltage is input to the multiplied voltage rectifier circuit, and the voltage output from the multiplied voltage rectifier circuit is also constant. The high voltage is maintained, and the capacitor 20 of the IGN circuit is efficiently charged.

In general, the AC voltage supplied to the discharge lamp 22 in the steady lighting state, that is, the AC voltage output from the DC / AC inverter has a frequency of about several hundred Hz, but the frequency of the output voltage of the transformers T1 and T2, that is, DC / The operating frequency of the DC converter is much higher than the frequency of the AC voltage described above, and charges can be accumulated in the capacitor in a short time by using the output voltages of the transformers T1 and T2. When the multiplied voltage rectifier circuit is operated using the output voltages of the transformers T1 and T2, a high voltage having a sufficient value can be generated even if the capacitances of the capacitors 10 to 12 constituting the circuit are set small. The multiplied voltage rectifier circuit can be miniaturized using a capacitor having a small outer dimension.
In addition, since the output voltage of the DC / DC converter and the output voltage of the multiplied voltage rectifier circuit are generated using the output voltages of the transformers T1 and T2 that are connected in parallel as viewed from the power source 1, the transformers T1 and T2 A voltage with little ripple can be generated, and noise generated with circuit operation can be suppressed.

As described above, according to the first embodiment, the multiplied voltage rectifier circuit is configured so as to generate a high voltage used for starting the discharge lamp 22 by inputting the potential difference between the output voltages of the two transformers T1 and T2. There is an effect that the number of parts can be reduced, the cost can be reduced and the size can be reduced.
Further, when the control unit 4 operates the transformers T1 and T2 with the ON duty of the switching elements 2 and 3 constant, and the capacitor 13 holding the output voltage of the DC / DC converter reaches the lighting voltage, the operation of the transformers T1 and T2 is performed. Since the voltage is applied to the capacitor 13 by operating the transformers T1 and T when the voltage becomes lower than the lighting voltage, a predetermined potential difference is input to the multiplied voltage rectifier circuit to generate a normal high voltage. Therefore, there is an effect that the capacitor 20 of the IGN circuit can be effectively charged.

1 is a circuit diagram of a discharge lamp lighting device according to Embodiment 1 of the present invention. FIG. 6 is an explanatory diagram showing the operation of the discharge lamp lighting device according to Embodiment 1. FIG. 6 is an explanatory diagram showing the operation of the discharge lamp lighting device according to Embodiment 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Power supply, 2, 3 Switching element, 4 Control part (control means), 5-9 Diode, 10-13 capacitor | condenser, 14-17 transistor, 18 Control part, 19 Resistance, 20 Capacitor, 21 GAP switch, 22 Discharge lamp.

Claims (4)

A plurality of DC / DC converters having a transformer for boosting the power supply voltage and connected in parallel;
Control means for controlling the operation of the transformer of each DC / DC converter;
A voltage multiplying voltage rectifier circuit that generates a high voltage used for starting a discharge lamp using a potential difference between output voltages of the transformers, and the control means shifts the operating phase of the transformers of the DC / DC converters. A discharge lamp lighting device, characterized in that it is controlled.   2. The discharge lamp lighting device according to claim 1, wherein the control means adjusts the operation phase and duty of the transformer of each DC / DC converter so that a potential difference inputted to the multiplied voltage rectifier circuit becomes large.   The control means stops the voltage output of the transformer when the voltage across the capacitor that holds the output voltage of the DC / DC converter at the lighting voltage of the discharge lamp reaches the lighting voltage, and the voltage across the capacitor becomes the lighting voltage. 3. The discharge lamp lighting device according to claim 1, wherein a voltage is output from the transformer when the voltage is smaller.   4. The discharge lamp according to claim 1, wherein the multiplied voltage rectifier circuit inputs a voltage from a secondary winding that generates a lighting voltage of the discharge lamp of each transformer. 5. Lighting device.

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